It is known that the most important dose-dependent effect of the so-called indirectly acting sympathomimetic amines belonging chemically to the class of phenylakylamines (e.g. the endogenous phenyl ethylamine (PEA) and tyramine) resides in the release of catecholamines--especially noradrenaline from the plasma stores of the neurons. Other non-endogenous phenylakylamines (e.g. amphetamine and metamphetamine) possess similar properties. Moreover, the noradrenaline releasing effect and depending on the dose the effects of other transmitter amines (e.g. serotonin) is strong and long lasting for metabolic reasons. Metamphetamine, also inhibits the neuronal uptake of indirectly acting endogenous sympathomimetic amines to a significant extent, but this effect is completely suppressed by noradrenaline release under in vivo conditions.